101
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Stendardi L, Grazzini M, Gigliotti F, Lotti P, Scano G. Dyspnea and leg effort during exercise. Respir Med 2005; 99:933-42. [PMID: 15950133 DOI: 10.1016/j.rmed.2005.02.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2004] [Indexed: 11/23/2022]
Abstract
Dyspnea and leg effort are the major symptoms limiting exercise in healthy subjects and in patients with a variety of respiratory disorders. Quantitative measurement of both symptoms may be obtained by category scales such as VAS and Borg, with the latter being widely used. Furthermore, descriptor clusters of dyspnea help to assess some of the reasons for stopping exercise. The intensity of dyspnea and leg effort are similar in different disease states; this symmetry suggests that the limiting discomfort is a function of the intensity of increased motor drive to peripheral and respiratory muscles. An alternative explanation for the factors which limit exercise is that the subjects stop exercise volitionally when the discomfort associated with continuing exercise exceeds that which they are willing to tolerate. Muscle strength contributes to the intensity of dyspnea and leg effort at a given power output: the greater the muscle force, the lower the symptom. Symptoms also correlate with intensity and duration of a task by a power function in such a way that when minimizing the intensity of a given muscular task by prolonging the duration of activity, the symptom is drastically reduced. Skeletal muscle fatigue may be a factor limiting exercise tolerance both in healthy subjects and in patients with cardiorespiratory disorders. In conclusion, symptom measurement complements physiological measurements, both being essential to a comprehensive understanding of exercise tolerance.
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102
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Troosters T, Casaburi R, Gosselink R, Decramer M. Pulmonary Rehabilitation in Chronic Obstructive Pulmonary Disease. Am J Respir Crit Care Med 2005; 172:19-38. [PMID: 15778487 DOI: 10.1164/rccm.200408-1109so] [Citation(s) in RCA: 295] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Thierry Troosters
- Respiratory Rehabilitation and Respiratory Division, UZ Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium.
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103
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Finucane KE, Panizza JA, Singh B. Efficiency of the normal human diaphragm with hyperinflation. J Appl Physiol (1985) 2005; 99:1402-11. [PMID: 15961606 DOI: 10.1152/japplphysiol.01165.2004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We evaluated an index of diaphragm efficiency (Eff(di)), diaphragm power output (Wdi) relative to electrical activation, in five healthy adults during tidal breathing at usual end-expiratory lung volume (EELV) and diaphragm length (L(di ee)) and at shorter L(di ee) during hyperinflation with expiratory positive airway pressure (EPAP). Measurements were repeated with an inspiratory threshold (7.5 cmH(2)O) plus resistive (6.5 cmH(2)O.l(-1).s) load. Wdi was the product of mean inspiratory transdiaphragmatic pressure (DeltaPdi(mean)), diaphragm volume displacement measured fluoroscopically, and 1/inspiratory duration (Ti(-1)). Diaphragm activation, measured with esophageal electrodes, was quantified by computing root-mean-square values (RMS(di)). With EPAP, 1) EELV increased [mean r(2) = 0.91 (SD 0.01)]; 2) in four subjects, L(di ee) decreased [mean r(2) = 0.85 (SD 0.07)] and mean Eff(di) decreased 34% per 10% decrease in L(di ee) (P < 0.001); and 3) in one subject, gastric pressure at EELV increased two- to threefold, L(di ee) was unchanged or increased, and Eff(di) increased at two of four levels of EPAP (P < or = 0.006, ANOVA). Inspiratory loading increased Wdi (P = 0.003) and RMS(di) (P = 0.004) with no change in Eff(di) (P = 0.63) or its relationship with L(di ee). Eff(di) was more accurate in defining changes in L(di ee) [(true positives + true negatives)/total = 0.78 (SD 0.13)] than DeltaPdi(mean).RMS(di)(-1), RMS(di), or DeltaPdi(mean).Ti (all <0.7, P < or = 0.05, without load). Thus Eff(di) was principally a function of L(di ee) independent of inspiratory loading, behavior consistent with muscle force-length-velocity properties. We conclude that Eff(di), measured during tidal breathing and in the absence of expiratory muscle activity at EELV, is a valid and accurate measure of diaphragm contractile function.
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Affiliation(s)
- Kevin E Finucane
- Department of Pulmonary Physiology, Sir Charles Gairdner Hospital, Western Australia.
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104
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Luo YM, Moxham J. Measurement of neural respiratory drive in patients with COPD. Respir Physiol Neurobiol 2005; 146:165-74. [PMID: 15766905 DOI: 10.1016/j.resp.2004.12.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2004] [Revised: 12/29/2004] [Accepted: 12/29/2004] [Indexed: 10/25/2022]
Abstract
Assessment of neural respiratory drive may be useful in patients with chronic obstructive pulmonary disease (COPD) for diverse clinical and academic reasons. We hypothesised that the oesophageal diaphragm EMG during CO2 rebreathing and treadmill exercise could be used for this purpose. The oesophageal catheter consisted of nine consecutive recording electrode coils, which formed five pairs of electrodes with an inter-electrode distance 3.2 cm within a recording pair. Each coil was 1cm in length and the gap between adjacent coils was 0.5 mm. Maximal isometric contractions at functional residual capacity (FRC) and maximal voluntary inspirations from FRC to total lung capacity (TLC) were performed. All subjects performed CO2 rebreathing until end-tidal CO2 was approximately 9% or they became intolerably breathless. There was a good linear relationship between peak of root mean square (RMS) of the diaphragm EMG and end-tidal CO2 (r = 0.92 +/- 0.06) during CO2 rebreathing. The method was also shown to be feasible during exercise. It is concluded that the diaphragm EMG recorded from an oesophageal electrode is a useful technique to assess neural respiratory drive in patients with COPD.
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Affiliation(s)
- Y M Luo
- Guangzhou Medical College, Guangzhou Institute of Respiratory Diseases, 151 Yanjiang Road, Post Code 510120, Guangzhou, China.
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105
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Spahija J, Beck J, de Marchie M, Comtois A, Sinderby C. Closed-Loop Control of Respiratory Drive Using Pressure-Support Ventilation. Am J Respir Crit Care Med 2005; 171:1009-14. [PMID: 15665323 DOI: 10.1164/rccm.200407-856oc] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
By using diaphragm electrical activity (multiple-array esophageal electrode) as an index of respiratory drive, and allowing such activity above or below a preset target range to indicate an increased or reduced demand for ventilatory assistance (target drive ventilation), we evaluated whether the level of pressure-support ventilation can be automatically adjusted in response to exercise-induced changes in ventilatory demand. Eleven healthy individuals breathed through a circuit (18 cm H2O/L/second inspiratory resistance at 1 L/second flow; 0.5-1.0 L/second expiratory flow limitation) connected to a modified ventilator. Subjects breathed for 6-minute periods at rest and during 20 and 40 W of bicycle exercise, with and without target drive ventilation (the target was set to 60% of the increase in diaphragm electrical activity observed between rest and 20 W of unassisted exercise). With target drive ventilation during exercise, the level of pressure-support ventilation was automatically increased, reaching 13.3 +/- 4.0 and 20.3 +/- 2.8 cm H2O during 20- and 40-W exercise, respectively, whereas diaphragm electrical activity was reduced to a level within the target range. Both diaphragmatic pressure-time product and end-tidal CO2 were significantly reduced with target drive ventilation at the end of the 20- (p < 0.01) and 40-W (p < 0.001) exercise periods. Minute ventilation was not altered. These results demonstrate that target drive ventilation can automatically adjust pressure-support ventilation, maintaining a constant neural drive and compensating for changes in respiratory demand.
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Affiliation(s)
- Jadranka Spahija
- Research Center, Respiratory Health Research Unit, Sacré-Coeur Hospital of Montreal, Canada H4J 1C5.
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106
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Hopkinson NS, Toma TP, Hansell DM, Goldstraw P, Moxham J, Geddes DM, Polkey MI. Effect of bronchoscopic lung volume reduction on dynamic hyperinflation and exercise in emphysema. Am J Respir Crit Care Med 2004; 171:453-60. [PMID: 15579725 DOI: 10.1164/rccm.200407-961oc] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Endobronchial valve placement improves pulmonary function in some patients with chronic obstructive pulmonary disease, but its effects on exercise physiology have not been investigated. In 19 patients with a mean (SD) FEV(1) of 28.4 (11.9)% predicted, studied before and 4 weeks after unilateral valve insertion, functional residual capacity decreased from 7.1 (1.5) to 6.6 (1.7) L (p = 0.03) and diffusing capacity rose from 3.3 (1.1) to 3.7 (1.2) mmol . minute(-1) . kPa(-1) (p = 0.03). Cycle endurance time at 80% of peak workload increased from 227 (129) to 315 (195) seconds (p = 0.03). This was associated with a reduction in end-expiratory lung volume at peak exercise from 7.6 (1.6) to 7.2 (1.7) L (p = 0.03). Using stepwise logistic regression analysis, a model containing changes in transfer factor and resting inspiratory capacity explained 81% of the variation in change in exercise time (p < 0.0001). The same variables were retained if the five patients with radiologic atelectasis were excluded from analysis. In a subgroup of patients in whom invasive measurements were performed, improvement in exercise capacity was associated with a reduction in lung compliance (r(2) = 0.43; p = 0.03) and isotime esophageal pressure-time product (r(2) = 0.47; p = 0.03). Endobronchial valve placement can improve lung volumes and gas transfer in patients with chronic obstructive pulmonary disease and prolong exercise time by reducing dynamic hyperinflation.
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Affiliation(s)
- Nicholas S Hopkinson
- Respiratory Muscle Laboratory, Department of Respiratory Medicine, Royal Brompton Hospital, Fulham Road, London SW3 6NP, UK.
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107
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Singh B, Panizza JA, Finucane KE. Diaphragm electromyogram root mean square response to hypercapnia and its intersubject and day-to-day variation. J Appl Physiol (1985) 2004; 98:274-81. [PMID: 15361515 DOI: 10.1152/japplphysiol.01380.2003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Diaphragm activation can be quantified by measuring the root mean square of crural EMG (RMSdi) (Beck J, Sinderby C, Lindstrom L, and Grassino A, J Appl Physiol 85: 1123-1134, 1998). To examine intersubject and day-to-day variation in the RMSdi-Pco(2) relationship, end-tidal Pco(2), minute ventilation (Ve), respiratory frequency (f(B)), and RMSdi were measured in seven healthy subjects on two occasions during steady-state ventilation at seven levels of inspired O(2) fraction (Fi(CO(2))) from 0 to 0.08 in random order. RMSdi was measured with a multielectrode esophageal catheter and controlled for signal contamination and diaphragm position. RMSdi was normalized for values obtained during quiet breathing at functional residual capacity, at Fi(CO(2)) of 0.04, and during an inspiratory capacity maneuver (RMSdi%max) as well as ECG R-wave amplitude at functional residual capacity (RMSdi/ECG(R)), f(B), and thickness of the costal diaphragm measured by ultrasound. RMSdi increased linearly with Pco(2) (mean r(2) = 0.83 +/- 0.10); at the highest Fi(CO(2)), RMSdi%max was 40.2 +/- 11.6%. Relative to the intersubject variation in the Ve-Pco(2) relationship, intersubject variations in the slopes and intercepts of the RMSdi-Pco(2) relationships were 1.7 and 1.8 times, respectively, and RMSdi%max-Pco(2) relationships 0.9 and 1.3 times, respectively, and were unrelated to f(B) and diaphragm thickness. Relative to the day-to-day variation in the Ve-Pco(2) relationship, day-to-day variation in the slopes and intercepts of the RMSdi-Pco(2) relationships were 2.8 and 4.4 times, respectively, and RMSdi/ECG(R)-Pco(2) relationships 1.3 and 2.2 times, respectively. It was concluded that the RMSdi-Pco(2) relationship measures chemosensitivity and is best compared between subjects via RMSdi%max and on separate occasions in the same subject via RMSdi/ECG(R).
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Affiliation(s)
- Bhajan Singh
- Dept. of Pulmonary Physiology, Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, WA 6009, Australia.
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108
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Man WDC, Mustfa N, Nikoletou D, Kaul S, Hart N, Rafferty GF, Donaldson N, Polkey MI, Moxham J. Effect of salmeterol on respiratory muscle activity during exercise in poorly reversible COPD. Thorax 2004; 59:471-6. [PMID: 15170026 PMCID: PMC1747047 DOI: 10.1136/thx.2003.019620] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Some patients with irreversible chronic obstructive pulmonary disease (COPD) experience subjective benefit from long acting bronchodilators without change in forced expiratory volume in 1 second (FEV(1)). Dynamic hyperinflation is an important determinant of exercise induced dyspnoea in COPD. We hypothesised that long acting bronchodilators improve symptoms by reducing dynamic hyperinflation and work of breathing, as measured by respiratory muscle pressure-time products. METHODS Sixteen patients with "irreversible" COPD (<10% improvement in FEV(1) following a bronchodilator challenge; mean FEV(1) 31.1% predicted) were recruited into a randomised, double blind, placebo controlled, crossover study of salmeterol (50 micro g twice a day). Treatment periods were of 2 weeks duration with a 2 week washout period. Primary outcome measures were end exercise isotime transdiaphragmatic pressure-time product and dynamic hyperinflation as measured by inspiratory capacity. RESULTS Salmeterol significantly reduced the transdiaphragmatic pressure-time product (294.5 v 348.6 cm H(2)O/s/min; p = 0.03), dynamic hyperinflation (0.22 v 0.33 litres; p = 0.002), and Borg scores during endurance treadmill walk (3.78 v 4.62; p = 0.02). There was no significant change in exercise endurance time. Improvements in isotime Borg score were significantly correlated to changes in tidal volume/oesophageal pressure swings, end expiratory lung volume, and inspiratory capacity, but not pressure-time products. CONCLUSIONS Despite apparent "non-reversibility" in spirometric parameters, long acting bronchodilators can cause both symptomatic and physiological improvement during exercise in severe COPD.
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Affiliation(s)
- W D C Man
- Respiratory Muscle Laboratory, Guy's, King's and St Thomas' School of Medicine, King's College Hospital, London, UK.
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109
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Binazzi B, Lanini B, Scano G. Assessing Respiratory Drive and Central Motor Pathway in Humans: Clinical Implications. Lung 2004; 182:91-100. [PMID: 15136883 DOI: 10.1007/s00408-003-1047-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/25/2003] [Indexed: 10/26/2022]
Abstract
Feedback from sensory elements as well as projection from higher Central Nervous System structures modify the level and pattern of motor outflow to the respiratory muscles and hence ventilation. In this review we describe the different methods to evaluate the degree to which higher centers determine the level and pattern of ventilation and coordinate use of the respiratory muscles in healthy humans and in patients with a number of respiratory disorders.
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Affiliation(s)
- B Binazzi
- Don C. Gnocchi Foundation (IRCCS), Section of Respiratory Rehabilitation, Pozzolatico, Florence, Italy
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110
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Duiverman ML, van Eykern LA, Vennik PW, Koëter GH, Maarsingh EJW, Wijkstra PJ. Reproducibility and responsiveness of a noninvasive EMG technique of the respiratory muscles in COPD patients and in healthy subjects. J Appl Physiol (1985) 2003; 96:1723-9. [PMID: 14660508 DOI: 10.1152/japplphysiol.00914.2003] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the present study, we assessed the reproducibility and responsiveness of transcutaneous electromyography (EMG) of the respiratory muscles in patients with chronic obstructive pulmonary disease (COPD) and healthy subjects during breathing against an inspiratory load. In seven healthy subjects and seven COPD patients, EMG signals of the frontal and dorsal diaphragm, intercostal muscles, abdominal muscles, and scalene muscles were derived on 2 different days, both during breathing at rest and during breathing through an inspiratory threshold device of 7, 14, and 21 cm H2O. For analysis, we used the logarithm of the ratio of the inspiratory activity during the subsequent loads and the activity at baseline [log EMG activity ratio (EMGAR)]. Reproducibility of the EMG was assessed by comparing the log EMGAR values measured at test days 1 and 2 in both groups. Responsiveness (sensitivity to change) of the EMG was assessed by comparing the log EMGAR values of the COPD patients to those of the healthy subjects at each load. During days 1 and 2, log EMGAR values of the diaphragm and the intercostal muscles correlated significantly. For the scalene muscles, significant correlations were found for the COPD patients. Although inspiratory muscle activity increased significantly during the subsequent loads in all participants, the COPD patients displayed a significantly greater increase in intercostal and left scalene muscle activity compared with the healthy subjects. In conclusion, the present study showed that the EMG technique is a reproducible and sensitive technique to assess breathing patterns in COPD patients and healthy subjects.
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Affiliation(s)
- Marieke L Duiverman
- Department of Pulmonary Diseases/Home Mechanical Ventilation, University Hospital Groningen, 9700 RB Groningen, The Netherlands.
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111
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Abstract
The act of breathing depends on coordinated activity of the respiratory muscles to generate subatmospheric pressure. This action is compromised by disease states affecting anatomical sites ranging from the cerebral cortex to the alveolar sac. Weakness of the respiratory muscles can dominate the clinical manifestations in the later stages of several primary neurologic and neuromuscular disorders in a manner unique to each disease state. Structural abnormalities of the thoracic cage, such as scoliosis or flail chest, interfere with the action of the respiratory muscles-again in a manner unique to each disease state. The hyperinflation that accompanies diseases of the airways interferes with the ability of the respiratory muscles to generate subatmospheric pressure and it increases the load on the respiratory muscles. Impaired respiratory muscle function is the most severe consequence of several newly described syndromes affecting critically ill patients. Research on the respiratory muscles embraces techniques of molecular biology, integrative physiology, and controlled clinical trials. A detailed understanding of disease states affecting the respiratory muscles is necessary for every physician who practices pulmonary medicine or critical care medicine.
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Affiliation(s)
- Franco Laghi
- Division of Pulmonary and Critical Care Medicine, Edward Hines, Jr. VA Hospital, 111 N. 5th Avenue and Roosevelt Road, Hines, IL 60141, USA.
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112
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Respiratory Muscle Unloading during Mechanical Ventilation. Intensive Care Med 2003. [DOI: 10.1007/978-1-4757-5548-0_27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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113
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Gorman RB, McKenzie DK, Pride NB, Tolman JF, Gandevia SC. Diaphragm length during tidal breathing in patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med 2002; 166:1461-9. [PMID: 12406839 DOI: 10.1164/rccm.200111-087oc] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Diaphragm function is compromised in severe chronic obstructive pulmonary disease (COPD) by hyperinflation, but its ability to shorten and contribute to tidal volume is uncertain. We estimated coronal diaphragm length by measuring zone of apposition length with ultrasound and rib cage diameters with magnetometers, in 10 male patients with severe COPD and 10 age- and sex-matched control subjects. Diaphragm length was 20% shorter in patients at residual volume (413 and 536 mm in patients and control subjects, respectively) and FRC (381 and 456 mm, respectively), but was not different at total lung capacity (312 and 336 mm, respectively). Zone of apposition length was reduced 50% at residual volume and FRC in patients, but was larger at a given absolute lung volume than in control subjects. There were no differences in tidal volume (0.8 L), tidal changes in zone of apposition length (20 mm) and diaphragm length (38 and 42 mm), and tidal volume displaced by the diaphragm (0.6 L), even though mean FRC in patients was similar to predicted total lung capacity. Although the diaphragm is shorter at FRC in patients with COPD, its motion and change in length during tidal breathing is similar to that in control subjects.
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Affiliation(s)
- Robert B Gorman
- Prince of Wales Medical Research Institute and University of New South Wales, Sydney, Australia
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114
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Ortega F, Toral J, Cejudo P, Villagomez R, Sánchez H, Castillo J, Montemayor T. Comparison of effects of strength and endurance training in patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med 2002; 166:669-74. [PMID: 12204863 DOI: 10.1164/rccm.2107081] [Citation(s) in RCA: 175] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We determined the effect of different exercise training modalities in patients with chronic obstructive pulmonary disease, including strength training (n = 17), endurance training (n = 16), and combined strength and endurance (n = 14) (half of the endurance and half of the strengthening exercises). Data were compared at baseline, the end of the 12-week exercise-training program, and 12 weeks later. Improvement in the walking distance was only significant in the strength group. Increases in submaximal exercise capacity for the endurance group were significantly higher than those observed in the strength group but were of similar magnitude than those in the combined training modality, which in turn were significantly higher than for the strength group. Increases in the strength of the muscle groups measured in five weight lifting exercises were significantly higher in the strength group than in the endurance group but were of similar magnitude than in the combined training group, which again showed significantly higher increases than subjects in the endurance group. Any training modality showed significant improvements of the breathlessness score and the dyspnea dimension of the chronic respiratory questionnaire. In conclusion, the combination of strength and endurance training seems an adequate training strategy for chronic obstructive pulmonary disease patients.
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Affiliation(s)
- Francisco Ortega
- Department of Pneumology, Hospital Universitario Virgen del Rocío, Sevilla, Spain.
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115
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Dempsey JA. Exercise carbon dioxide retention in chronic obstructive pulmonary disease: a case for ventilation/perfusion mismatch combined with hyperinflation. Am J Respir Crit Care Med 2002; 166:634-5. [PMID: 12204854 DOI: 10.1164/rccm.2206001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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116
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117
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Tobin MJ. Sleep-disordered breathing, control of breathing, respiratory muscles, and pulmonary function testing in AJRCCM 2001. Am J Respir Crit Care Med 2002; 165:584-97. [PMID: 11874806 DOI: 10.1164/ajrccm.165.5.2201061] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Martin J Tobin
- Division of Pulmonary and Critical Care Medicine, Hines Veterans Affairs Hospital, Route 11N, Hines, Illinois 60141, USA.
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118
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Tobin MJ. Chronic obstructive pulmonary disease, pollution, pulmonary vascular disease, transplantation, pleural disease, and lung cancer in AJRCCM 2001. Am J Respir Crit Care Med 2002; 165:642-62. [PMID: 11874810 DOI: 10.1164/ajrccm.165.5.2201065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Martin J Tobin
- Division of Pulmonary and Critical Care Medicine, Hines Veterans Affairs Hospital, Route 11N, Hines, Illinois 60141, USA.
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119
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Beck J, Gottfried SB, Navalesi P, Skrobik Y, Comtois N, Rossini M, Sinderby C. Electrical activity of the diaphragm during pressure support ventilation in acute respiratory failure. Am J Respir Crit Care Med 2001; 164:419-24. [PMID: 11500343 DOI: 10.1164/ajrccm.164.3.2009018] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We compared crural diaphragm electrical activity (EAdi) with transdiaphragmatic pressure (Pdi) during varying levels of pressure support ventilation (PS) in 13 intubated patients. With changing PS, we found no evidence for changes in neuromechanical coupling of the diaphragm. From lowest to highest PS (2 cm H(2)O +/- 4 to 20 cm H(2)O +/- 7), tidal volume increased from 430 ml +/- 180 to 527 ml +/- 180 (p < 0.001). The inspiratory volume calculated during the period when EAdi increased to its peak did not change from 276 +/- 147 to 277 +/- 162 ml, p = 0.976. Respiratory rate decreased from 23.9 (+/- 7) to 21.3 (+/- 7) breaths/min (p = 0.015). EAdi and Pdi decreased proportionally by adding PS (r = 0.84 and r = 0.90, for mean and peak values, respectively). Mean and peak EAdi decreased (p < 0.001) by 33 +/- 21% (mean +/- SD) and 37 +/- 23% with the addition of 10 cm H(2)O of PS, similar to the decrease in the mean and peak Pdi (p < 0.001) observed (34 +/- 36 and 35 +/- 23%). We also found that ventilator assist continued during the diaphragm deactivation period, a phenomenon that was further exaggerated at higher PS levels. We conclude that EAdi is a valid measurement of neural drive to the diaphragm in acute respiratory failure.
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Affiliation(s)
- J Beck
- Hôpital Ste-Justine, Department of Pediatrics, Montreal, Quebec, Canada.
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